how do you stop/cope with a DDos attack?

there's a guy on youtube, "woodysgamertag" that does various live streams which have a lot of subscribers so in the call of duty world at least, he's a celebrity if that's the right word. he has over 1.1 million subscribers & youtube is his living.

he can't livestream any more as he keeps getting DDos attacks which take down the stream.

i just wondered (& so's he for that matter) how you stop it happening or even if you can stop it.

He could always go onto a separate connection and live stream via Youtube instead of through his own internet connection. Performing a DDOS attack on something like Youtube isnt going to have much of an effect unless you're hitting it with millions of PCs